Messages in this thread | | | Date | Mon, 22 Jul 2019 10:20:03 -0600 | From | Lina Iyer <> | Subject | Re: [PATCH 1/2] drivers: qcom: rpmh-rsc: simplify TCS locking |
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On Fri, Jul 19 2019 at 12:20 -0600, Stephen Boyd wrote: >Quoting Lina Iyer (2019-07-01 08:29:06) >> From: "Raju P.L.S.S.S.N" <rplsssn@codeaurora.org> >> >> tcs->lock was introduced to serialize access with in TCS group. But >> even without tcs->lock, drv->lock is serving the same purpose. So >> use a single drv->lock. > >Isn't the downside now that we're going to be serializing access to the >different TCSes when two are being written in parallel or waited on? I >thought that was the whole point of splitting the lock into a TCS lock >and a general "driver" lock that protects the global driver state vs. >the specific TCS state. > Yes but we were holding the drv->lock as well as tcs->lock for the most critical of the path anyways (writing to TCS). The added complexity doesn't seem to help reduce the latency that it expected to reduce. >> >> Other optimizations include - >> - Remove locking around clear_bit() in IRQ handler. clear_bit() is >> atomic. >> - Remove redundant read of TCS registers. >> - Use spin_lock instead of _irq variants as the locks are not held >> in interrupt context. > >Can you please split this patch up into 3 or 4 different patches? I'm >not sure why any of these patches are marked with Fixes either. It's an >optimization patch, not a fix patch, unless the optimization is really >large somehow? > Okay. I will try that. >> >> Fixes: 658628 ("drivers: qcom: rpmh-rsc: add RPMH controller for QCOM >> SoCs") >> Signed-off-by: Raju P.L.S.S.S.N <rplsssn@codeaurora.org> >> Signed-off-by: Lina Iyer <ilina@codeaurora.org> >> --- >> drivers/soc/qcom/rpmh-internal.h | 2 -- >> drivers/soc/qcom/rpmh-rsc.c | 37 +++++++++++--------------------- >> drivers/soc/qcom/rpmh.c | 20 +++++++---------- >> 3 files changed, 21 insertions(+), 38 deletions(-) >> >> diff --git a/drivers/soc/qcom/rpmh-internal.h b/drivers/soc/qcom/rpmh-internal.h >> index a7bbbb67991c..969d5030860e 100644 >> --- a/drivers/soc/qcom/rpmh-internal.h >> +++ b/drivers/soc/qcom/rpmh-internal.h >> diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c >> index e278fc11fe5c..92461311aef3 100644 >> --- a/drivers/soc/qcom/rpmh-rsc.c >> +++ b/drivers/soc/qcom/rpmh-rsc.c >> @@ -93,8 +93,7 @@ static void write_tcs_reg_sync(struct rsc_drv *drv, int reg, int tcs_id, >> >> static bool tcs_is_free(struct rsc_drv *drv, int tcs_id) >> { >> - return !test_bit(tcs_id, drv->tcs_in_use) && >> - read_tcs_reg(drv, RSC_DRV_STATUS, tcs_id, 0); >> + return !test_bit(tcs_id, drv->tcs_in_use); > >This can be a diffedjusted rent patch. Why is reading the tcs register >redundant? Please put that information in the commit text. > The tcs_in_use, is adjusted along with the DRV_STS and reading the tcs_in_use should be enough.
Thanks for your review Stephen.
--Lina
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